Study On Damage Characteristics Of Vulnerable Parts Of Ship Under Secondary Explosion Impact

With the background of ship vulnerability research and the need to improve the damage capability of underwater anti-ship weapons,this paper studies the damage characteristics of vulnerable parts of ships under secondary explosive impact,aiming at the damage of vulnerable parts of ships and ship targets under the action of secondary discontinuous impact.The main work and research conclusions of this paper are as follows:In order to obtain the rule of secondary cumulative damage of vulnerable parts,a simple tensile structural part was selected for numerical simulation calculation,and the primary and secondary impact damage characteristics of the tensile part under constant and explosive loads were analyzed.The research showed that the damage of the tensile part was necking fracture,and the fracture time of the tensile part under explosive impact load was earlier than that under constant load,and the fracture load threshold was larger,The fracture position is closer to the boundary of the applied load;There is a rule of secondary cumulative damage of tensile specimen under constant load and explosive load.When the primary load strength is small,the secondary load strength of specimen fracture is basically unchanged;When the primary load increases to a certain extent,the secondary load that causes the specimen to fracture decreases with the increase of the primary load,and the decreasing trend gradually increases.The research results provide support for the analysis of secondary impact damage characteristics of more complex structures.Based on the analysis of the secondary impact damage characteristics of the tensile parts,the marine vibration isolator is selected as a typical vulnerable part to carry out the research on the secondary impact vibration damage law of the vibration isolator.The dynamic response characteristics of the vibration isolator under the primary and secondary impact vibration are analyzed by numerical simulation,and the cumulative damage law of the secondary impact of the vibration isolator is obtained,and the secondary impact damage threshold model of the vibration isolator is constructed.The research shows that the impact vibration damage of the vibration isolator is represented by the plastic deformation and even fracture of the connecting bolt,and the secondary cumulative damage is represented by the plastic strain of the bolt under the primary load,which leads to the decrease of the fracture threshold,and then the fracture occurs under the secondary load;The peak value of bolt breaking load is less affected by the vibration attenuation coefficient and more affected by the vibration frequency.The higher the vibration frequency is,the greater the secondary peak value of the isolator damage is;At the same vibration frequency,with the increase of the peak value of the primary load,the threshold value of the peak value of the secondary load of the isolator damage gradually decreases,and the decreasing trend continues to increase.The constructed threshold model provides support for the research of ship damage based on vibration isolator damage.In order to obtain the damage law of the ship based on the damage of the vibration isolator under the underwater explosion,the research on the dynamic response of the underwater explosion of the ship hull and the vibration damage law of the vibration isolator on the ship was carried out,and the simulation model of the dynamic response of the underwater explosion of the ship hull was established with reference to the typical surface ship structure,and the impact vibration response of the ship hull under the underwater explosion in different directions was calculated and analyzed,Combined with the shock response simulation model of vibration isolator and the damage threshold model of secondary shock,the damage criterion of ship secondary explosion shock based on vibration isolator damage is obtained.The results show that the amplitude of hull impact response is the largest in the area directly opposite the explosion point and attenuates rapidly to the surrounding area.In a single explosion,only the vulnerable parts of the ship near the explosion point are vulnerable to damage;The vulnerable parts of the ship are mainly distributed in the middle of the ship.The bow and stern of the ship are not vulnerable to damage.The range of vulnerable parts of the secondary explosion is increased.The research provides data support for the damage assessment of ship secondary underwater explosion based on vibration isolator damage.The damage assessment of ship secondary underwater explosion based on isolator damage was carried out.Combined with the established damage criteria of ship secondary explosion shock based on isolator damage,the damage assessment model of ship based on isolator shock vibration damage was established,and the impact of factors such as the distribution of detonation point and vulnerable parts,and the impact of single and two hits on the damage probability was analyzed.The results show that the probability of ship damage under the condition of two hits is significantly higher than that of single hit;The more vulnerable parts of the ship or the more concentrated in the middle of the ship,the higher the probability of damage of the ship,regardless of single or two hits;Under the condition of two hits,when the two hit points do not overlap,the damage probability of the ship is higher.The conclusions obtained can provide a reference for the in-depth study of the damage assessment of multi-missile-life underwater ships,as well as the optimization of the anti-ship combat strategy and the amount of missiles used.